83 FR 17077 - Special Conditions: Bell Helicopter Textron, Inc. (BHTI), Model 525 Helicopter; Mode Annunciation

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 83, Issue 75 (April 18, 2018)

These special conditions are issued for the BHTI Model 525 helicopter. This helicopter will have a novel or unusual design feature associated with fly-by-wire flight control system (FBW FCS) functions that affect the pilot awareness of the flight control modes while operating the helicopter. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.

[Federal Register Volume 83, Number 75 (Wednesday, April 18, 2018)]
[Rules and Regulations]
[Pages 17077-17078]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2018-08139]



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Rules and Regulations
                                                Federal Register
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Federal Register / Vol. 83, No. 75 / Wednesday, April 18, 2018 / 
Rules and Regulations

[[Page 17077]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 29

[Docket No. FAA-2017-1129; Notice No. 29-042-SC]


Special Conditions: Bell Helicopter Textron, Inc. (BHTI), Model 
525 Helicopter; Mode Annunciation

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the BHTI Model 525 
helicopter. This helicopter will have a novel or unusual design feature 
associated with fly-by-wire flight control system (FBW FCS) functions 
that affect the pilot awareness of the flight control modes while 
operating the helicopter. The applicable airworthiness regulations do 
not contain adequate or appropriate safety standards for this design 
feature. These special conditions contain the additional safety 
standards that the Administrator considers necessary to establish a 
level of safety equivalent to that established by the existing 
airworthiness standards.

DATES: April 18, 2018.

FOR FURTHER INFORMATION CONTACT: George Harrum, Aerospace Engineer, 
Rotorcraft Standards Branch, Policy and Innovation Division, FAA, 10101 
Hillwood Pkwy., Fort Worth, TX 76177; telephone (817) 222-4087; email 
[email protected].

SUPPLEMENTARY INFORMATION:

Background

    On December 15, 2011, BHTI applied for a type certificate for a new 
transport category helicopter designated as the Model 525. The aircraft 
is a medium twin-engine rotorcraft. The design maximum takeoff weight 
is 20,500 pounds, with a maximum capacity of 19 passengers and a crew 
of 2.
    The BHTI Model 525 helicopter will be equipped with a four-axis 
full authority digital FBW FCS that provides for aircraft control 
through pilot input and coupled flight director modes. Current 
regulations are inadequate in the area of pilot awareness of the flight 
control modes while operating the helicopter. The proposed special 
condition will require that suitable mode annunciation be provided to 
the flight crew for events that significantly change the operating mode 
of the system but do not merit the traditional warnings, cautions, and 
advisories.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, BHTI must show that the Model 
525 helicopter meets the applicable provisions of part 29, as amended 
by Amendment 29-1 through 29-55 thereto. The BHTI Model 525 
certification basis date is December 31, 2013, the effective date of 
application to the FAA.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 29) do not contain adequate or 
appropriate safety standards for the BHTI Model 525 because of a novel 
or unusual design feature, special conditions are prescribed under the 
provisions of Sec.  21.16.
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for that model be amended 
later to include any other model that incorporates the same or similar 
novel or unusual design feature, the special conditions would also 
apply to the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the BHTI Model 525 helicopter must comply with the noise 
certification requirements of 14 CFR part 36, and the FAA must issue a 
finding of regulatory adequacy under section 611 of Public Law 92-574, 
the ``Noise Control Act of 1972.''
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type-
certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The BHTI Model 525 helicopter will incorporate the following novel 
or unusual design features: A four-axis full authority digital FBW FCS. 
Pilot control inputs, through the mechanically linked cockpit controls 
(cyclic, collective, directional pedals), are transmitted electrically 
to each of the three Flight Control Computers (FCCs). The pilot control 
input signals are then processed and transmitted to the hydraulic 
flight control actuators which affect control of the main and tail 
rotors. The FCCs process the pilot control input signals depending on 
the flight control mode in affect.

Discussion

    The current 14 CFR 29 standards do not provide adequate standards 
for pilot awareness of the flight control modes while operating the 
helicopter. These special conditions require that suitable mode 
annunciation be provided to the flight crew for events that 
significantly change the operating mode of the system but do not merit 
the traditional warnings, cautions, and advisories.

Discussion of Comments

    Notice of proposed special conditions No. 29-042-SC for the BHTI 
Model 525 helicopter was published in the Federal Register on December 
7, 2017 (82 FR 57687). One commenter, Sikorsky Aircraft (Sikorsky), 
responded to the Notice.
    Sikorsky requested that the annunciation required by the proposed 
special conditions be placed within the immediate field of view of the 
pilot. Sikorsky also requested that because the word ``significantly'' 
in the proposed special conditions may be subjective, the following 
language be added to provide clarification: ``in such a way as to alter 
the pilots primary control strategy.''
    The FAA agrees. We have revised the special conditions accordingly.

Applicability

    As discussed above, these special conditions are applicable to the 
BHTI Model 525 helicopter. Should BHTI apply at a later date for a 
change to the type certificate to include another model incorporating 
the same novel or unusual design feature, these special conditions 
would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of rotorcraft. It is not a rule of general applicability.

[[Page 17078]]

List of Subjects in 14 CFR Part 29

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

    The authority citation for these special conditions is as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Special Conditions

0
 Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for the Bell Helicopter Textron, Inc., 
Model 525 helicopter:
    Mode Annunciation: A means must be provided, within the pilots' 
primary field of view, to indicate to the crew any mode that 
significantly changes or degrades the handling or operational 
characteristics of the rotorcraft in such a way as to alter the pilots' 
primary control strategy.

    Issued in Fort Worth, Texas, on March 30, 2018.
Jorge Castillo,
Acting Manager, Rotorcraft Standards Branch, Policy and Innovation 
Division, Aircraft Certification Service.
[FR Doc. 2018-08139 Filed 4-17-18; 8:45 am]
 BILLING CODE 4910-13-P